Origin and Habitat: 110 km North-North-East of Keetmanshoop, Namibia.
Habitat: It grows on gravelly plains and flats in calcareous soil thickly strewn with smooth, white pebbles and which this Lithops resembles to an unbelievable degree, this camouflage allows them to escape detection and is a very effective strategy for escaping predation. They are pollinated by bees, flies, wasps, gnats, bugs and other insects that are common in the area.

• Lithops vallis-mariae C166 110 km NNE of Keetmanshoop, Namibia

• Lithops vallis-mariae (Dinter & Schwantes) N.E.Br.
• Lithops villetii var. deboeri (Schwantes) D.T.Cole
• Mesembryanthemum vallis-mariae Dinter & Schwantes
• Lithops vallis-mariae C060 30 km SSW of Mariental, Namibia
• Lithops vallis-mariae C066 20 km E of Gibeon Station, Namibia
• Lithops vallis-mariae C166 110 km NNE of Keetmanshoop, Namibia
• Lithops vallis-mariae C167 (syn. margarethae) TL: Near Berseba, Namibia
• Lithops vallis-mariae C182 125 km N of Keetmanshoop, Namibia
• Lithops vallis-mariae C238 85 km NE of Keetmanshoop, Namibia
• Lithops vallis-mariae C281 TL: 15 km E of Mariental, Namibia
• Lithops vallis-mariae C282 125 km North of Keetmanshoop, Namibia.
• Lithops vallis-mariae C296 40 km SSE of Koës, Namibia
• Lithops vallis-mariae var. margarethae (Dinter & Schwantes) N.E.Br.

• Lithops vallis-mariae cv. Valley Girl S.A.Hammer

Description: This peculiar species is characterised by a minutely pitted top surface, which appears uniform to the naked eye, consists in reality of a large number of ridges with vermiform convolutions. These peculiar vermiform ridges have the appearance of fine sintered limestone and only found in this species.
Habit: It is an acaulescent perennial, geophytic, succulent, seldom solitary, usually forming clumps of 2-4 head, occasionally with up 10 or more heads.
Bodies (Paired leaves): Medium sized, compact, obconic, truncate in profile, slightly convex; 25-40 mm long, 20-30 mm broad, fissure shallow, faces reniform, slightly rugose, opaque pale grey-white, or grey-white tinged with creamy yellow, green, beige or pink and very minutely wrinkled or dotted with pin-pricks. Top with many depressions, giving the appearance of a large number of dots or points. Margin and windows absent or very obscure or very opaque, yellowish-white to bluish-white. Islands manifest only as areas enclosed by channels. Channel often absent, very thin, sometimes quite deeply pitted, channels opaque to very obscurely translucent grey, bluish grey, pinkish grey or pinkish brown, Rub absent.
Flowers: Daisy-like, diurnal, small 15-30 mm in diameter, yellow, straw yellow, sometimes orange-yellow, may be tinged with bronze or pink.
Blooming season: Autumn (in habitat blooms in April)
Fruits: Mostly 5-chambered capsules, profile boat-shaped, flat, occasionally slightly convex, faces broadly elliptic.

Bibliography: Major refences and further lectures
1) Heidrun E. K. Hartmann “Aizoaceae F – Z” Springer 2002
2) Achim Hecktheuer “Mesembs, mehr als nur Lithops” Books on Demand GmbH Norderstedt. 2008
3) Desmond T. Cole & Naureen A. Cole, Uwe Beyer, Yves Delange “Les Lithops” SUCCULENTES Spécial 2008 AIAPS (now Terra seca). 2008
4) Desmond T. Cole & Naureen A. Cole “LITHOPS Flowering Stones” Cactus & Co. Libri. 2005
5) Yasuhiko Shimada “The Genus Lithops” Dobun Shoin. 2001
6) Rudolf Heine “Lithops - Lebende Steine” Neumann Verlag. 1986
7) Bernd Schlösser “Lithops – Lebende Steine” Praktische Anleitung für die Zimmerkultur. BussinessPoint MEDIA. 2000
8) Steven A. Hammer “Lithops – Treasures of the veld” British Cactus and Succulent Society. 1999
9) Desmond T. Cole “Lithops – Flowering Stones” Acorn Books 1988
10) Rudolf Heine “Lithops – lebende Steine” Neumann Verlag. 1986
11) David L. Sprechman “Lithops” Associated University Presses, Inc. 1970
12) Gert Cornelius Nel “Lithops” Hortors Limited, South Africa 1946
13) Edgar Lamb "The illustrated reference on cacti and other succulents" Blandford Press. 1978
14) Christopher Brickell, Royal Horticultural Society "RHS A-Z Encyclopedia of Garden Plants: K-Z., Volume 2" Kindersley, 2008
15) G. C . Nel “Lithops: Plantae succulantae, rarissimae, in terra obscuratae, e famailia Aizoaceae, ex Africa australi” Hortors Limited, Cape Town, South Africa 1946
16) Heidrun E. K. Hartmann "Illustrated Handbook of Succulent Plants: Aizoaceae F-Z" Springer, 2002
17) Steven A. Hammer "Lithops: Joyaux du veld" Editions Quae, 25/nov/2010
18) Doreen Court “Succulent Flora of Southern Africa” Struik Nature, 2010

Cultivation and Propagation: In the winter season the plant doesn’t need watering. At this time it extracts water from the outer succulent leaves, allowing them to shrivel away, and relocating water to the rest of the plant, and to the new leaves that form during this period. This plant does best in a well-lit area (Bright shade to full sun). Water sparingly only in warm, weather. Don't water when it's cold.